FediTips has moved!Unfortunately this is true for any online service, even the biggest and most stable sites will sometimes go nuts and do weird things (https://www.forbes.com/sites/mattnovak/2023/08/19/twitter-deletes-all-user-photos-and-links-from-2011-2014/ and https://www.theguardian.com/technology/2019/mar/18/myspace-loses-all-content-uploaded-before-2016).
Ultimately the only absolute guarantees are if you run the service yourself (which I try to help people with on https://growyourown.services) or use a distributed social network like @manyver_se where the data is stored on your phone or your computer.
All GNU social JP content and data are available under the